local mma = math.max
local n = io.read("*n")
local dp1, dp2 = {}, {}
for i = 1, 10 do
  dp1[i] = -1000000007
  dp2[i] = -1000000007
end
dp1[10] = 0
for _z = 1, n do
  local a = io.read("*n")
  local src = _z % 2 == 1 and dp1 or dp2
  local dst = _z % 2 == 1 and dp2 or dp1
  for i = 1, 10 do
    dst[i] = src[i]
  end
  a = a % 10
  for i = 1, 10 do
    local j = i + a
    if 10 < j then j = j - 10 end
    dst[j] = mma(dst[j], src[i] + 1)
  end
end
local tbl = n % 2 == 1 and dp2 or dp1
print(tbl[10])